Mixed polyvinyl acetal resin



Patented Jan. 6, 1942 aztazr:

mxan ronrvnwr. ACETAL RESIN Llames G. MeNall'y and Russel H. Van Dyke,

Rochester, N. Y., assignors to Eastman Kodak Company,-Rochester, N. L, a corporation of New Jersey No Drawing. Application January '29, 1938,

a Serial No. 187,718

12 Claims.

This invention relates to synthetic resins and more particularly to what can be called polyvinyl acetal resins in which the acetal linkages are formed from a plurality of aldehydes and/or cyclic ketones. More accurately, the resins of this invention can be called polyvinyl acetal resins in which the acetal linkages are formed from a plurality of aldehyde acetal groups and/or cyclic ketone acetal groups. This application is a con-- tinuation-in-part of our copending application Serial No. 47,472, filed October .30, 1935. v

Simple polyvinyl acetal ,resins (i. e., those in which the acetal linkages are formed from but one kind of aldehyde acetal group or cyclic ketone acetal group) have been prepared from polyvinyl alcohols by condensation of aldehydes or cyclic ketones therewith, in the presence of an acetal condensation catalyst. Simple poly vinyl acetal resins have also been prepared by concomitantly deesterifying a polyvinyl ester and condensing the deesterifled product with aldehydes, in the presence of a deesterification catalyst, the catalyst serving to accelerate also the condensation of the deesterified product with the aldehyde. The polyvinyl acetaldehyde acetal resins, prepared from polyvinyl alcohol and acetaldehyde, for example, are probably the most interesting of the simple polyvinyl acetal resins. These acetaldehyde acetal resins appeared to be useful for a variety of purposes in the plastics field. For example, these acetaldehyde acetal resins can be cast from ordinary simple solutions into the form of transparent film or sheet. However, the film or sheet is too brittle to be adapted commercially to certain uses; for instance, the film or sheet is too brittle to serve as a support for light-sensitive photographic coatings. Efforts to decrease the brittleness of such resins by changing the chemical composition'thereof, viz., by increasing the hydroxyl group content, resulted in resins which were too water susceptible. Formaldehyde acetal resins have many properties desirable in plastic materials, but possess a peculiar affinity for the relatively few organic .solvents in which they are soluble, which characteristic practically precludes their adaptation to a number of commercial processes. aldehyde acetal resins are fairly thermoplastic substances, so that their use is considerably limiterl. Benzaldehyde acetals prepared by the Butyrprior art processes have very high softening points, relative to the aforesaid'simple polyvinyl to a number of processes.

the usual organic solvents and hence are of limited utility.

We have now found a new group oi. polyvinyl acetal resins which possess new characteristics permitting the resins to be adapted commercially In our new resins, the acetal linkages are formed from a plurality of aldehydes and/or cyclic ketones. By means of our invention, acetaldehyde acetal resins having greatly improved flexibility without loss of moisture resistance are made available, formaldehyde acetal resins having greatly improved solubility and solvent retention characteristics are provided and benzaldehyde acetal resins having improved solubilities in organic solvents are made available for the first time.

It is, accordingly, an object of our invention to provide new polyvinyl acetal resins. It is a further object of our invention to provide new polyvinyl acetal resins in which the acetal linkages are formed from'a plurality of aldehyde acetal and/or cyclic ketone acetal linkages, which resins have characteristics permitting the adaptation of the resins to a variety of commercial processes. It is a further object of our invention to provide a process for preparing our new resins. Other more specific objects will become apparent hereinafter.

According to our invention, we prepare our new resins by treating a polyvinyl compound containing hydroxyl groups with a plurality of aldehydes and/or cyclic ketones, in. the presence of an acetal condensation catalyst. We can employ a polyvinyl ester as a starting material and concomitantly deesterify the ester and condense the deesterifled product with a plurality of aldehydes and/or cyclic ketones. Our new resins always contain a hydroxyl group content which is advantageously not in excess of that equivalent to about 15% by weight of polyvinyl alcohol. The

ester group content, if any, of our new resins is advantageously not more than that equivalent to about 10% by weight 'of polyvinyl ester and is preferably 5% or less. Those of our new resins having sticking points, as determined by the metransparent film or sheet to be used as a support for light-sensitive photographic coatings, is that group in which'the acetal linkages are formed from a plurality of aliphatic aldehyde acetal acetal resins, but have very limited solubilities in groups containing up to four carbon atoms, such as formaldehyde, acetaldehyde, chloracetaldehyde, propionaldehyde, butyraldehyde and isobu-' tyraldehyde acetal groups, for example. Among such resins, the hydroxyl group content is advantageously not more than about that equivalent to 15% by weight. of polyvinyl alcohol and is beneficially 10 to 7% by weight or less, and

- the ester group-content, if'any, islikewise advantageously not more than that equivalent to about 10% by weight ofpolyvinylester. Prefer-e ably, the ester group content is to 1% or less.

- A very useful group of these resins wherein the acetal linkages are formed from a plurality of aldehyde acetal groups containing not more than four carbon atoms is made up of those in which from about to about 50 mol. percent of the total acetal linkages-are formed from propionaldelwde, butyraldehyde, and/or isobutyraldehyde acetal groups, while the remainder of the acetal linkages are formed from. aldehyde acetal groups containing from one to two carbon atoms, such as formaldehyde, acetaldehyde or chloracetaldehyde acetal groups, for example. Acetaldehyde acetal resins in which from about to about mol. percent of the acetal linkages are formed from butyraldehyde or isobutyraldehyde .acetal groups are particularly useful for the manufacture of the aforesaid support for photographic coatings and are the invention of Ralph H. Talbot (see a copending application Serial No. 85,733, filed June 16, 1936, now United States Patent 2,129,450, dated Sept. 6, 1938) and Donald R. Swan (see his copending application Serial N0. 262,029, filed March 15, 1939).

ascaarv While the process of making our new resins is subject to variation, particularly as respects the nature and quantity of the starting polyvinyl compound employed, the nature and quantity of the aldehyde or cyclic ketone employed, the nature and quantity of the acetal condensation catalyst employed, the nature and quantity of the deosterification agent employed, if any, the nature and quantity of deesteriflcation catalyst employed, if any, and the method of isolation and purification of the resins. the following exfrom one to two carbon atoms, such as formaldehyde, acetaldehyde or chloracetaldehyde acetal groups, for example. In thisgroup of resins the hydroxyl group content is advantageously not more than that equivalent to about 10% by weight of polyvinyl alcohol, while theester group content is likewise advantageously not more than that equivalent to about 10% of polyvinyl ester and is preferably 5% or lower. Resins of this group are also useful in the manufacture of transparent film or sheet intended as a support for photographic coatings. Still another particularly useful group of our new resins is made up of those in which from about 10 to about mol. percent of acetal linkages are formed from aromatic aldehyde acetal groups and the remainder are formed from aromatic aldehyde acetal groups, particularly aliphatic aldehyde acetal groups having not more than four carbon atoms, such as formaldehyde, acetaldehyde, chloracetaldehyde, propionaldehyde, butyraldehyde, or isobutyraldehyde acetal groups. for example. Acetaldehyde-benzaldehyde acetal resins are particularly useful in the manufacture of transparent film or sheet intended as a support for light-sensitive photographic coatings. In

. these resins containing aromatic aldehyde acetal groups, the ester group content is advantageously not greater than that equivalent to about 10% by weight of polyvinyl ester and is preferably 5 to 1% or less. The hydroxyl groupcontent is advantageously not more than that equivalent to about 12 to 15% by weight of polyvinyl alcohol and is beneficially 8% or less.

amples will serve to illustrate the 'mode of obtaining our new resins. These examples are not intended to limit our invention. In the examples, the degree of polymerization of the polyvinyl ester employed is indicated by stating the viscosity in centipoises of its 10% solution in benzene at 25 C.

hyde acetal resins Into each of four glass stoppled containers,

were placed 50 ms. of a polyvinyl acetate (30 centipoises), and, to each container were added 62 cc. of ethyl alcohol (95%), 15 cc. of water and2 cc. of hydrochloric acid (sp. g. 1.18). When most of the lumps were dissolved, there was added various mixtures of trioiwmethylene (polymeric formaldehyde) and paraldehyde (polymeric acetaldehyde) as shown below. Each was stirred thoroughly before placing in an oven maintained at 70 C.

la. 12 gms. of trioxymethylene and 4.4 gms. of paraldehyde were added. Heating at 70 vC. waseflected for 48 hours. At the end of this time, the resin was precipitated. in hot water, washed and dried. Yield 27 gms. Soluble in a mixture of ethylene dichloride (75%) and methyl alcohol (25%). This resin was converted into a clear film which was characterized by its low lent to about 3.7% by weight of polyvinyl acetate and a hydroxyl group content equivalent to about 12.1% by weight of polyvinyl alcohol.

17). 9 gms. of trioxymethylene and 8.8 gms. of paraldehyde were added. Heating at 70 C. was effected for 48 hours. The resin was precipitated in hot water, washed and dried. Yield 28 gms. Soluble in mixtures of ethylene dichloride and methyl alcohol. This resin was converted into a film characterized by its excellent clarity and the ease-with which it could be stripped from the film-forming'surface.

1c. 6 gms. of trioxymethylene and 13.2 gms. of

paraldehyde were added. Heating was effected at 70 C. for 48' hours. The resin"was precipitated in hot water, washed and dried. Yield 30 gms. Soluble in mixtures of ethylene dichloride 'in mixtures of ethylene dichloride and methyl This resin was converted into a film alcohol. characterized by its excellent clarity and high resistance to tear.

Any of the above four procedures canine dupli f cated employing as starting materiaha compound which already has a substantial hydroxyl group content, for example, a partially or substantially completely hydrolyzed polyvinyl acetate. In'

these above procedures and in the following examples, the reagents employed, such as ethyl alpolyvinyl alcohol.

the contaminating acid, alcohol and unreacted trioxymethylene to be washed out. Precipitation in hot water facilitates this washing out of impurities. The precipitation can also be carried out in dilute ammonium hydroxide. Even when the thread method of precipitation is employed, the thread-like precipitate settles to a cake. This cake can be comminuted and further washed. In these above procedures, the volatile reagents used are held in the reaction mixture by using a closed reaction vessel. However, the same result can be attained by using a reaction vessel equipped with a reflux condenser.

EXAMPLE 2.Polyvinyl formacetdldehyde acetal resin The resin was then precipitated in hot water,

washed and dried. Soluble in mixtures of ethylene chloride and methyl alcohol. This resin was converted into a clear film characterized by its resistance to tear and a satisfactory tensile strength. This resin had an acetate group content equivalent to about 5.8 percent by weight of polyvinyl acetate and a hydroxyl group content equivalent to about 13.6 percent by weight of In a similar manner, a polyvinyl formaldehyde-cyclohexanone acetal resin can be prepared employing 50 gms. of polyvinyl acetate, 8 gms. of trioxymethylene and 7.4 gm. of cyclohexanone.

ExsmnLr-z 3.Polyvinyl jonnacetaldehude acetal resin 50 gms. of a polyvinyl acetate (30 centipoises) were treated exactly as in Example 2, except that 6 gms. or trioxymethylene and 5.8 gms. oi paraldehyde were used. Soluble in-mixtures of ethylene chloride and methyl alcohol. This resin was converted into a clear film characterized byits excellent resistance to tear.

ExAmLs 4.PoZ1 vinyl formacetaldehyde acetal resin 50 gms. of a polyvinyl acetate (30 centipoises) were treated exactly as in Example 2, except that 4 gms. oi. trioxymethylene and 8.8 gms. of paraldehyde were used. Soluble in mixtures of ethylene chloride and methyl alcohol. The resin was converteddnto a clear film characterized by its high tensile strength. This resin had an acetate I were treated exactly as in E mple 2, except that 2 gms. of trioxymethylene an 11.7 gms. of paraldehyde were used. Soluble in a mixture made up of 75% ethylene chloride and 25% methyl alco- 5 hol. This resin was converted into a clearfilm, the film showing rather marked susceptibility to water.

EXAMPLE 6.Polyvinyl formacetaldehydi: acetal resm 50 gms. of a polyvinyl acetate (45 centipoises).

were treated exactly as in Example 1, except that 9 gms. of trioxymethylene and 8.8 gms. o1 paralclehyde were used. Soluble in ethylene chloride as well as mixtures of ethylene chloride with methyl alcohol. The resin was converted into a very thin film, characterized by its high tensile strength, high resistance to tear and low water susceptibility. This resin had an acetate group content equivalent to about 5.7 percent'by'weight of polyvinylacetate and a hydroxyl group content equivalent to about 13.1 percent by weight ofpolyvinyl alcohol.

resin 50 gms. of a polyvinyl acetate centipoises) were added to 15 cc. of water, 6200. of ethyl alcohol (95%) and 2 cc. of hydrochloric acid (sp. g.

1.18). The whole was digested at 70 C. until solution was complete. 6 gm. of trioxymethylene were added and digestion continued at 70 C. for

about 16 hours. 13 gms. of benzaldehyde -were added and digestion continued for about 48 hours at 70 C. The resin was precipitated in hot water, washed and dried. This resin is of particular use in molding. Small cups were successfully molded at 150C. and a pressure of 10,000 lbs. per square inch. These cups were resilient and could be machined well.

EXAMPLE 8.--Polyvinyl ,formbutyraldehyde acetal resin gms. of a polyvinyl acetate (30 centipoises) were treated with water, alcohol and hydrochloric acid exactly as in Example 7. When solution was complete 6 gms. of trioxymethylene were added and digestion at 70 C. continued for about 16 hours. 10gms. of butyraldehyde were added and digestion continued for about 48 hours at 70 C. The resin was precipitated in hot water,

washed and dried. Soluble in mixtures of ethylene chloride and methyl alcohol. This resin gave a very clear film, characterized by high resistance to tear. This resin also molded well. In a similar manner, a polyvinyl acetbutyraldehyde acetal resin can be made by condensing 50 gms. of a polyvinyl acetate (30 centipoises) and 8.8 gms. of paraldehyde and 10 gms. of butyraldehyde. This resin had an acetate group content equivalent to about 3.9 percent by weight of polyvinyl acetate and a hydroxyl group content equivalent to about 14.4 percent by weight of polyvinyl alcohol. 0f the total acetal linkages 65 mole percent were butyraldehyde acetal linkages.

EXAMPLE 9.--POZyvinyl formb'utyraldehyde acct-a resin 50 gm. of a polyvinyl acetate (30 centipoises) gver'e treated exactly as in Example 8, except thatgms. of trioxymethylene and 18 gms. of butyral- ,dehyde were used. Solublein mixtures of ethylene chloride and methyl alcohol. The resin was converted into a very clear film, characterized 7 by its high resistance to tear. This resin had an r Examrnr: 7.Polym'nyl formbenzaldehyde acetal 4 2. 9. 1 e acetate group content equivalent to about 5.1 aheavy viscous pasteremained. 20 cc. of hydro- P rcent by weight of polyvinyl acetate and. a;;-\ chloricacidisp.ggjildal'and 100 ce.cr water'were hydroxyl group-content equivalent to about'l3.8 l added and thelwhole allowed to stand at room percent by weight or polyvinyl alcohol. temperature until .a,homogene'ous solution was rm-ch obtained. 3 glass! p lialdehyde and 8 of E n Polyvinyl to trioxymethy1ene were added and allowed to stand ctr-cam temperatureior 32 hours. Precipitated in hot-water, washed' anddried. This resin had were dissolved in 15 cc. of water-{62 cc..of ethylhigh m ti point and as luble'in mixtures alcohol (95%) and 20 cc. of hydrochl r c M d 1 =01 ethylene chloride andmethyl alcohol. This sp. g. 1.18). The whole was diaestedlat C- resin hadyery useful properties, but the difficulty 'untilfsolution was complete. 6 oi trioxy- I in obtaining polyvinyl acetate 01' a viscosity at 60 methylene were added anddigestlon was 0011-. centipoiseslimitsitsapplication.

tinued at 70 C. for about-18 hours. 10 of c crotonaldehyde and 18 sins. of hydrochloric acid m 'f (sp.'g.-=1.18) were added and; digestion continued 1" dehflde m f r about five and one-half hours- Therwnwas Y lo lbsi 'c't polyvinyl acetate (25 centlpoises) precipitated with hot water. washed and driedwere dissolved in 25 lbs. of 95% ethyl alcohol. To

Exlunnn ls- Polyvinyl jormucetaldehyde' ature .until solution was complete. 18 ms. of tri- Decomwsiiion at melting P t- Resln-insoluthis solution were added 2.6 lbs. tr fi-hydroxyl n m st r ani s lvents h n an xcess of 20 butyraldehyde -'(aldol), 3.8 lbs. or paraldehyde hydrochloric a d W avoided p yvlnyl formand 2.5 lbs." of hydrochloric acid (sp. g. 1.18). cr tollal ehyde acetal resin was formed. The resulting. mixture was allowed to stand at resin was more soluble in Or anic sol l 40 C. for about four days. At the end oi this Exmlls 1 arm mldeh de time the reaction mixture was diluted with about g f ,u y two volumesxoi 95% ethyl alcohol. The diluted reaction mixture was slowly poured into water to 50 gms. of a polyvinyl acetate centipoises) preclpitateythe resin The resin was washed with dissdved in 15 water- 0f ethyl water-tcrremcve acid and dried at 14o= F. to 160 alcohol (95%) and 2 cc. of hydrochloric acid (sp. E e resin 1 had an acetate group 7 content g. 1.18).. When solution was complete, 12 ms. of 30 equivalent-t0 about. v by weight of polyvinyl trioxymethylene and m mrfuraldehyde alcohol and a hydroxyl group content equivalent were added and digestion at 70 C. eflected for to, about-113% by weight of polyvinyl alcohoh about 24 hours. The resin was precipitated in 1 hot water, washed and dried. This resin had de- M L 6 v l/l i ehr -h ptaldesirable properties, except that it developed color. 5 11 Metal 188m EXAMPLE mM imhyde m t l 344 of polyvinyl acetate (25 centipoises) resin" 400 e so a o in a IG creatures (s 84 dissolvedin 34 cc. or water. The were added to 120 cc. of water, 496 cc. of ethyl almixture :w'g 'j g e with stirring at about 0 Q Lfrc thissolut'l were added 34 g. or sulfuric acid .Were dissolvedin 800 cc. oiethyl alcohol (95%).

cohol (95%) and 16 cc. of hydrochloric acid (sp. for three w four hours -,1; incipient precfpjtas- 1 -18 he. wh w s o d Stand at room I tion. At this time as 9.. of paraldehyde were temperature 3 complefie? 72 added and heating at 70 C. was continued for 8 01 trioxymethylene and 0.4 Ems. of par about: three hours, 35 g. of heptaldehyde were dehyde were added and the'whole diges 5 then added and heating at 70 C. continued for 70 C. 101388 hours. The resin wasprecipit d about three hours longer. The reaction mixture hot water. w h d n dried- T resin w 0 was diluted with about three times its volume of uble in res of thylene chl01fi d m l ethyl alcohol (95%) Sufllcient sodium hydroxalcohol and. converted n o of highly ide was added to neutralize the suliuric acid eatfi -Physie8 r ert h m, alyst. The neutralized solution was poured into molded l '2 v cool water to precipitate. The resin was washed thoroughly and dried. The resin had-an acetate resin. group. YQ ntent equivalent to about 18.8% by weight of polyvinyl acetate and a hydroxyl group 100 gms. or a polyvinyl a etate (45 centimisesl content equivalent to about 10.5% by weight of were added to ,80 cc. 0! water, 124 .cc.( of ethylislpolyvinyl alcohol. co c1 and 4 cc. othydrochloric acid sp. '3. The whole was allowed to stand 47mm temper? EXAMPLE l7.-Polyment zilll geiglropzonaldehyde accxymetb leneand 17.6, ma-Ticrparaldeh 'de were "f20 lbs'. of polyvinyl acetate 45 centipoises) added and the wholedigested at C. for 88 were dissolved in 50 lbs. of ethyl alcohol.

i -Political vat-anathema Jet-ah hours. The was precipitatedin l otviut't'er and washed and dried. This resinfwas, soluble". in mixtures of ethylene chloride: :and alcohol. It had the same properties of the resin given inExamplel2 lidin-additlon hadahigher meltingpoint.

trite dissolyediintilo cc.Iof a mixture of equal vb jn'l'sfot water and 9.5% ethyl alcohol. To the resulting: solution, -6.4 lbs. of propionaldehyde and 8.2 lbs. of paraldehyde and 3.0 lbs. of hydrochloric acid (sp. g. 1.18) were added. The whole mixture was maintained at 40 C. for about seven days. At this time the reaction mixture was dires n 70 luted with about 2.5 volumes of 95% ethyl am To this solution was added. 0.2 lb. of sodium ni- 50 cms. of polyvinyl acetate (60 centipoises) hol. The resin was then precipitated by slowly were addedto ethyl. alcohol (95%) and-heated on pouring the diluted reaction mixture into cold the steam bath. adding additional alcohol from water. The resin was then washed with cold time to time. When the excessively hardlumps water to remove acid and then was dried at were dissolved. the alcohol evaporated until 7 to 1 This resin containedan acetate group aeeacn content equivalent to about 6.3% by weight of polyvinyl acetate and a hydroxylgroup content Exurrrs 18.Plyvinyl acetaldehzlde-propionaldehyde-butyraldehyde acetal resin 20 lbs. of polyvinyl acetate (45 centipoises), were dissolved in 50 lbs. of ethyl alcohol (95%).

To this solution was added 0.2 lb. of sodium nitrite dissolved in 300 cc. of aqueous ethyl alcohol (50%). To the resulting solution were then added, with stirring, 2.7 lbs. of propionaldehyde, 3.8 lbs. of butyraldehyde and 6.1 lbs. of paraldehyde, followed by 3 lbs. of hydrochloric acid (sp. g. 1.18). The whole mixture was allowed to stand at 40 C. for about seven days. The reaction mixture was then diluted with 3.5 times its volume of ethyl alcohol (95%). The diluted reaction mixture was poured into cool 'water to precipitate the resin. The resin was thoroughly washed with water and dried at 140 to 160 F. The resin had an acetate group content equivalent to about 6.4% by weight of polyvinyl acetate and a hydroxyl group content equivalent to about 7.8% by weight of polyvinyl alcohol.

Exsmrra 19.--Polyvinyl acetaldehyde-veratraldehyde acetal resin 150 g. of polyvinyl acetate (25. centipoises) were dissolved in 375 cc. of ethyl alcohol (95%).

. To this solution were added 87 g. of veratraldehyde, 53.2 g. of paraldehyde and 37.5 g. of hydrochloric acid (sprg. 1.18). The mixture was allowed to stand at 40 C. for about four days. The reaction mixture was diluted with one and a quarter times its. volume of ethyl alcohol (95%) The diluted reaction mixture was poured into water to precipitate the resin. The'resin was thoroughly washed with water and dried at Exaurrr: 20.-Polyvinyl acetaldehyde-cyclopentanone acetal resin 1'72 g. of polyvinyl acetate (25 centipoises) were dissolved in 500 cc. of ethyl alcohol (95%).

days. The reaction mixture was diluted with twice its volume of ethyl alcohol. The diluted reaction mixture was poured into water to pre cipitate the resin. The resin was thoroughly washed with water and dried at 140 to 160 F. The resin contained a hydroxyl group content equivalent to about 11.2 percent by weight oi polyvinyl alcohol and an acetate group content equivalent to about 3.9% by weight of polyvinyl acetate.

. EXAMPLE fle -Polyvinyl acetfurjuraldehyde acetal resin 150 g. of polyvinyl acetate (25 centipoises) were dissolved in 375 g. ofethyl alcohol (95%). To this solution were added 69.2 g. oi paraldehyde, 16.6 g. of iurfuraldehyde and 37.5 g. of hydrochloric acid (sp. g. 1.18). The mixture was allowed to stand at 40 C. for three days. The reaction mixture was 'diluted with twice its volume of ethyl alcohol. The diluted reaction mixture was poured into water to precipitate the resin. The resin was thoroughly washed with water and dried at 140 to 160 F. The resin contained a hydroxyl group content equivalent EXAMPLE 23.--Polyvinyl acetaldehyde-benzaldehyde acetal resin 200 g. of .polyvinyl acetate (25 centipoises) hyde and g. of hydrochloric acid (sp. g. 1.18) This mixture was allowed to stand at 40 C. for

-- about four days. At the end of this time the To this solution were added 100 g. 01 cyclopentanone, 44 g. of paraldehyde, 3.5 g. of hydroxylamine hydrochloride and 45 cc. of hydrochloric acid (sp. g. 1.18). The mixture was allowed to stand at 40 C. for about four days. The reac- (SD. 8. 1.18). about four days at 40 C. At the end of this time tion mixture was diluted with twice its volume dried. The resin had an acetate group content equivalent to about 2.8% by weight oi! polyvinyl acetate and a hydroxyl group content equivalent to about 14.6% by weight of polyvinyl alcohol.

.The hydroxylamine hydrochloride is used to improve stability of the resin. Exaurrs 21.Polyvin1ll acetaldehyde-fnrjuralde hyde acetal resin 150 g. of polyvinyl acetate (25 centipoises) were dissolved in 3'75 g. of ethyl alcohol (95%). To this solution were added 66.4 g. of paraldeq hyde and 46.1 g. of furfuraldehyde and 37.5 g.-

of hydrochloric acid (sp. g. 1.18). The mixture was allowed to stand at 40 C. for about three reaction'mixture was diluted with 2.5 times its volume of- 95% ethyl alcohol. The diluted reaction mixture was poured into water to precipitate the resin. The resin was thoroughly washed with water and dried. This resin had an acetate group content equivalent to about 5.6% by weight of polyvinyl acetate and a hydroxyl group content equivalent to about 13.4% by weight of polyvinyl alcohol. Exmru: 24.Polyvinyl acetaldehyde' benzaldehyde acetal resin 25 lbs. of polyvinyl acetate were dissolved in lbs. oi ethyl alcohol. To this solution were added 11.25 lbs. of, benzaldehyde, 11.25 lbs. of paraldehyde and 6.25 lbs. of hydrochloric acid The solution was allowed to stand content equivalent to about 2% by weight of polyvinyl acetate.

ExAHPLr: 25.-Polmn'nyl butymldehyde-benzaldehyde acetal resin g. of polyvinyl acetate (45 centipoises) were dissolved in 960 g. of 95% ethyl alcohol. To this solution were added 118 g. 01' benzaldehyde and 186 g. of butyraldehyde and 80 g. of hydrochloric acid (sp. g. 1.18). The resulting solution was allowed to stand for about eight days at 40 C.

The reaction mixture was then diluted with.

about twice its volumeoi; 95% ethyl alcohol. :The diluted reaction mixture was poured intocold water to precipitate the rain. The resin thoroughly washed with water and dried. The

resin had a hydroxyl' group content equivalent to about 7.4% .by weight of polyvinyl alcohol and acetate group content equivalent .about.2.2% by weight of polyvinyl. acetate and illyomx l: group content equivalent to, about I. 7.8% by wcisht oi P lyvinyl alcohol.

an acetate group content equivalent to abcut 5.65% by weight oi polyvinyl acetate. I In a. similar manner, employing 79.8 g. of

' benzaldehyde instead or 118. g. and 214 g. oi

butyraldehyde instead of 186 g., a resin having a.

hydroxyl group content equivalent to about 8.1%

Exnrru benealdehudeacetqlresin 29.-Polyci1wl acetaldehyde-o-chloro- 1:50 part of, polyvinyl mat;- (25centipoises) werl. dissolved in 375 parts of 95% ethyl alcohol.

by weight of polyvinyl alcohol and an acetate Exerrrtx 26.--Polyvinyl acetaldehyde-isovoleroldehude acetal resin 172 g. of polyvinyl acetate (25 centipoises) were dissolved in 500 cc. of 95% ethyl alcohol.

To this solution wereadded with stirring 73 parts of o-chlorobenzaldehyde and 54 parts of paraldehyde and 37.5 parts of hydrochloric acid (sp. g. 1 1.18). The resulting solution was allowed to stand at about 40C. tor about 5 days. At the "end of this time the reaction mixture was poured into water to precipitate the resin. The resin was thoroughly washed with water and dried at 140 to 160 1". This resincontained an acetate group content equivalent to about .2 percent by 4 weight. oi polyvinyl alcohol and a hydroxyl group content equivalent to' about 9percentby' weight oipolyvinylalcoholv Exams 30.-Polyvinyl' acetaldehyde-m-nitro- To this solution were added 52 g. of isovaleraldehyde and 62 g. 01 paraldehyde and 43 cc. of hydrochloric acid (sp. g. 1.18). The resulting solution was allowed to stand at 40 C. for about four days. The reaction mixture was then diluted with about twice its volume of 95% ethyl alcohol. The diluted reaction mixture was poured into cold water to precipitate the resin. The resin was thoroughly washed with water and dried at 50 C. for about twenty-four hours. The resin had a hydroxyl group content equivalent to about 8.7% by weight oi polyvinyl alcohol and an acetate group content equivalent to about 4.0% by weight of polyvinyl acetate.

EXAMPLE 2'7.Polyvinyl' acetaldehyde-isobutyraldehyde acetal resin 210 g. of polyvinyl acetate was dissolved in 500 g. of methanol. To this solution were added this time the reaction mixture was diluted with benzaldehude acetal resin t 150 parts oi polyviny1 acetate (25 centipoises) were dissolvedin 875 parts of 95% oi ethyl alcohol. To this solution were added with stirring 79 parts or m-nitrobenzaldehydeand 54 parts oi paraldehyde and 37.5 parts of hydrochloric acid (sp. g. 1.18) The resulting solution was allowed to stand at about C. for about 5 days. I At the end of this time the reaction mixture was poured into water to precipitate the resin. The resin was thoroughly washed with water and dried at 140 to 160 1". This resin contained an acetate group content equivalent to about 4 percent by weight about twice its volume of 95% ethanol. The; diluted reaction mixture was poured into cold water to precipitate the resin. The precipitated resin was thoroughly washed with water and dried at 50 C. for about twenty-four hours. The Y resin had an acetate group content equivalent-to about 2.5% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 11.8% by weight of polyvinyl alcohol.

Exsm u: 28.Poluvim l aoetazaenuae-z otnyzbutyraldehyde acetal resin 172 g. of polyvinyl acetate (25 centipoises) were dissolved in 500 cc. of ethyl alcohol. To this solution were added 62 g. of paraldehyde, g. of 2- ethylbutyraldehyde and 50 cc. of hydrochloric acid (sp. g. 1.18). The-resulting sclutionwas about of polyvinyl acetate and a hydroxyl group content equlvalent-toabogtp percent by weight of polyvinyl alcohol. The oi Examples 29 and are the invention oi Martti Salc.

,Exnnt: 31.'-Polwlnyl acetaldehude-c'hloracetaldehyde acetal resin 107 g. of polyvinyl acetate (viscosity 30) were dissolved ing. of ethyl acetate and 113 g. of ethylalcohol. To this solution was added with stirring g. of the diethyl acetal of monochloracetaldehydeand'lb cc. of sulfuric acid dissolved in 16 cc. of water. The resulting mixture was heated at about 70 C. for-about 8 hours with stirring. The reaction mixture was then cooled to ordinary temperatures and diluted with twice its volumeoi'v IA-di'oxan'e, plus enough ammoniumihydroxideto neutralize the suliuric' acid present. reaction mixture was then poured into well agitated cold water to precipitate the resin. The resin was thoroughly washed with cold water-and then dried at about 50 C.

l The resin was soluble in acetone, in butyl alcodisperse in metnvl or ethyl alcohol.

hol and in chlorinated hydrocarbons. It did not The resin contained an acetate group content equivalent to about. 11 percent by weight of polyvinyl acetate and a hydroxyl group content equivalent to about 15.4 percent by weight of polyvinyl alcohol. 15 percent of the weight of the resin was due to chlorine. :Resins containing chloracetaldehyde acetal groups are the inventions of Donald R. Swan (see his copending application Serial No. 248,515,- illedDecember 30, 1938. now'United States Patent 2,213,750; dated September 3, 1940) Resins oi Examples 28, 27 and 28 are also the invention of Donald R. Swan (see hiscopending dried '"at lof C. for twenty-tour hours. The resin 75 muss-con 1939).

N 1 29. illed March 15,

The rates of reaction of the various aldehydes and cyclic ketones are generally difierent, depending upon the natures of the aldehydes and/ or cyclic ketones and the conditions employed. The

only satisfactory method of determining what ratio of aldehydes and/or cyclic ketones in the reaction mixture produces a resin of desired ratio or aldehyde and/or cyclic ketone acetal groups is to carry out a test preparation, isolate and purify the resin and determine by analysis the ratio of aldehyde and/or cyclic ketone acetal groups in the resin. Generally, in our new resins, each acetal group constitutes at least about ten molepercent of the total acetal linkages.

The polyvinyl esters employed in our process can be of any desired viscosity. Polyvinyl esters of yiscosities ranging from 15 to 45 are readily available. v

When preparing our new resins from polyvinyl alcohols, the polyvinyl alcohol is advantageously suspended in a lower aliphatic alcohol, such as isopropyl for example, and to the suspension the aldehydes and/or cyclic ketones and acetal condensation catalyst added. Agitation of the reactants is necessary. Advantageously, however, our new resins are made from polyvinyl esters as illustrated in the above examples.

the quantity and nature of materials used as Acid deesteriflcation catalysts are well known and any of these can be employed in our process. Mineral acids, such as hydrochloric or sulfuric acid are advantageously employed. Trichloraceticand aromatic sulfonic acids, for ex-. ample, are less satisfactory because the deesterifications proceed more slowly in their presence. Acid deesteriflcation catalysts are well known as acetal condensation catalysts. Acid reacting salts, such as aluminum and zinc chloride, for example, are also well known acetal condensation catalysts. These salts, however, are not suitable deesteriflcation catalysts. Phosphoric acid is a well known deesteriflcation catalyst. The quantity of deesteriflcation and acetal condensation catalysts is important. Depending upon the nature of the catalyst, larger amounts tend to produce color in the resin.

The polyvinyl ester employed is advantageously the readily available and less costly polyvinyl acetate. Polyvinyl formate is advantageously avoided. Polyvinyl propionate or benzoate can be employed, for example. The polyvinyl ester employedneed not be a simple polymer but can as well be a conjoint polymer, such as polyvinyl acetate-propionate, for example. Any polyvinyl compound having readily deesterifiable groups can be employed. When carrying out our process with a polyvinyl alcohol, any polyvinyl alcohol,

suchas that formeclby partial or complete deesteriflcation of a polyvinyl ester can be employed.-

The polyvinyl compound used as starting material must either have a substantial proport on of ester groups which deesterify readily to give hydroxyl groups, or the starting polyvinyl compound must have a substantial proportion of hydroxyl groups to begin with.

When either a polyvinyl ester or a polyvinyl alcohol is employed, the, condensation with the aldehydes and/or cyclic ketones can best be carried out in the presence of an organic solvent. such as ethyl alcohol, acetone. acet c acid or ethyl acetate. Any reaction medium which gives rise to a single homogeneous phase and hence a rapid and smooth reaction will sufilce. Lower aliphatic alcohols, i. e., those having one to four carbon atoms, particularly the primary monodiluents, viz., acetone, ethyl acetate and the like, have an eflfect on the resins produced. In the reaction of a polyvinyl ester with a plurality of aldehydes and/or cyclic ketones, if too little water is employed the resulting resin tends to be colored.

If too much water is present, the reaction mixture gives rise to a precipitate prior to the completion of the reaction.

When such precipitation occurs, the resulting substance is high in hydroxyl group content, 1. e., acetalization was substantially incomplete. Such substances are not without utility, sinc their higher hydroxyl group content tends to make them water soluble. They can be used as dispersing, wetting or sizing agents. I

The aldehydes and/or cyclic ketones employed can be the simple monomeric forms or polymeric forms. In the case of the lower aliphatic aldehydes, the polymeric forms are much more conveniently handled. The aldehydes and/or cyclic ketones can also be employed in the form of derivatives which function as the aldehydes or cyclic ketones under the conditions of the reaction. For example, acetaldehyde can be employed inthe form of the diethyl acetal of acetaldehyde. If such derivatives are liquid in nature, an'excess can be used, thereby providing a convenient reaction medium.

The polyvinyl alcohol or polyvinyl ester can be treated with a plurality of aldehydes and/or cyclic ketones simultaneously or the different carbonyl. compounds can be added successively. We have found the properties of the resulting polyvinyl acetal resins diifer according to whether the carbonyl compounds are reacted simultaneously or successively. This is especially noticeable when formaldehyde is used along with someother carbonyl compound or compounds. We have found it more satisfactory to add the formaldehyde first, allow it toreact, and then add the second carbonyl compound. If desired, a third carbonyl compound can be added.

As illustrated in the above examples, these new resins can be prepared under various conditions of temperature. Where temperatures above room temperature are employed, a means for preventing the loss of the volatile solvents used must be provided. At C. a reflux condenser or closed reaction vessel serves this purpose.

The mixed polyvinyl acetal resins which show satisfactory solubility in organic solvents can be converted into film or sheet as indicated in various of the above examples. This is done by dissolving about 1 part by weight of the resin in from about 4 to 5 parts by weight of a suitable organic solvent, which may be a single solvent or a mixture of solvents, and the resulting solution or dope" is coated out to desired thinness on a film forming surface, such as a glass or metal plate or table or revolving drum. When the solvent has evaporated (this can be conveniently accelerated by means of warm air) the resulting film or sheet is stripped from the flhn forming surface and subjected to curing (removal of excess solvent) by heating in warm air. 01 the resulting cured films or sheets, several 'of those made from resins illustrated above are useful as ample photographic emulsions. An example of a resin which furnishes a highly desirable support for photographic emulsions is that illustrated in Example 12.

Most of the herein described new resins are especially satisfactorily soluble in mixtures of alkylene chlorides, such as ethlyene chloride, and

' high percentage oxygen compounds, such as lower aliphatic alcohols, lower aliphatic ketones, lower aliphatic esters, lower aliphatic acetals, lower aliphatic ethers, dioxane, etc. From, such solvents, the resin can be coated'out into film or sheet and then cured.

Plasticizers can be incorporated in the resins prior to formation of the film or sheet. The follacquers with or without the addition of other resinous bodies. Almost any property desired in the permanent coating resulting from such varnishes or lacquers can be obtained by selecting a suitable mixed polyvinyl acetal resin. These new mixed polyvinyl acetal resins and, more particu-- larly, those of lower melting points, can be successfully applied to the manufacture of laminated sheets of materials, such as glass, cellulose nitrate,'cellul0se acetate or wood. These new resins can also be used to impregnate fabrics, wood and the like," for the purposes of waterproofing and preservation. These new resins can also be used to insulate conductors of electricity.

In the field of textiles, these resins have a wide range of utility. Those containing a high hydroxyl group content can be used as dispersing,

sizing and wetting agents. The resins containing a lower hydroxyl group content can be precipitated from solution in the form of threads or sheets alone, or in conjunction with cellulose derivatives. These new resins can also be extruded into the form of film or sheet. The resulting film or sheet made by extrusion as well as by coating from solutions of the resins can be laminated and pressed into the form of heavier sheeting or boards.

Mixed polyvinyl acetal resins in which the acetal linkages are formed in part'from aromatic and/or heterocyclic aldehydes and in part from aliphatic aldehydes are also described in our coabout fifteen percent b weight of poylvinyl alcohol and an acetate content equivalent to not more than about percent by weight of polyvinyl acetate.

3. A polyvinyl acetal resin in which the acetal linkages are formed from a plurality of different aliphatic aldehyde acetal groups having not more than four carbon atoms. each of said acetal groups constituting at least ten mole percent of the total acetal linkages, said having a' hydroxyl gro'up content equivalent to not more than about fifteen per cent by weight of polyvinyl alcohol and an ester group content equivalent .to not more than about ten per cent by weight of polyvinyl ester.

4. A polyvinyl acetal-resin in which the acetal linkages are formed in part from formaldehyde and in part from acetaldehyde, said resin having a hydroxyl group content equivalent to not more than about fifteen percent by weight of polyvinyl alcohol and an ester group content equivalent to not more than about ten percent by wei ht of polyvinyl ester. i

5. A polyvinyl acetal reslnin'tvliich *the linkages are formed in part from formaldehyde and in part from butyraldehyde, said resin having a hydroxyl group content equivalent to not more than about fifteen per cent by weight of polyvinyl alcohol and an ester group content equivalent to not more than about ten'percent by weight of polyvinyl ester.

6. A polyvinyl acetal resin in which the acetal I linkages are formed in part from -acetaldehyde and in part from butyraldehyde, said resin having a hydroxyl group content equivalent to not more than about fifteen percent by weight of I polyvinyl alcohol and an ester group content equivalent to not more than about ten percent by weight of polyvinyl ester.

7. A process of making mixed polyvinyl. resins which comprises condensing a hydrolysis product of a polyvinyl ester with an amount of an aldehyde less than will combine with the hydrolysis product and when said aldehyde is substantially all combined with the hydrolysis product condensing the mass with a diijferent aldehydein amount in excess of that which can combine with the unreacted hydrolysis product present during said second condensation.

8. A process for preparing polyvinyl acetal resins comprising reacting a polyvinyl ester with a plurality of diiferent aldehydes, in the presence of a deesterification medium and an acid pending application Serial No. 187,717, filed of even date herewith. What we claim as our invention and desire to be secured by Letters Patent of the United States is:

1. A polyvinyl acetal resin in which the acetal linkages are formed from a plurality of difi'erent aliphatic aldehyde acetal groups having not more than four carbon atoms, said resin having ahydroxyl group content equivalent to not more than about fifteen percent by weight of polyvinyl alcohol and an ester group content equivalent to not more than about ten percentby weight "of. Polyvinyl ester. I

2. A polyvinyl acetal resin in which the acetal linkages are. formed from a plurality of different aliphati'c'aldeliyde acetal groups having not more than four carbon atoms, said resin having a hydroxyl group content equivalent to'not more than 75' deesteriflcation catalyst, the reaction being carried out with all of the reactants and reaction products in solution in the deesterification medium, until there is obtained a polyvinyl acetal having an'ester group content equivalent to not more than about ten percent by weight of polyvinyl ester and a hydroxyl group content equivalent to not more than about fifteen percent by weight of polyvinyl alcohol.

9. A process for preparing polyvinyl acetal resins comprising reacting a polyvinyl ester with r a plurality of different aldehydes, in the presence of a deesterification medium and an acid deesterification catalyst, the, aldehydes being reacted-with ester successively, the reaction tants deesterification medium, until there is obtained a polyvinyl acetal. having anfester group content equivalent to not more than about percent by weight of polyvinyl ester and a hydroxyl outwith-allot the reacand reactlonproduots-insolution in the group content equivalent to not more than about fifteen percent by weight of polyvinyl alcohol.

10. A process for preparing polyvinyl acetal resins comprising reacting a polyvinyl ester with formaldehyde and with another aldehyde, in the presence of a deesterification medium and an acid deesterification catalyst, the formaldehyde being reacted substantially completely before the other aldehyde is reacted, the reaction being carried out with all of the reactants and reaction products in solution in the deesterification medium, until there is obtained a polyvinyl acetal having an ester group content equivalent to not more than about ten percent by'weight of polyvinyl ester and a hydroxyl group content equivalent to not more than about fifteen per cent by weight of polyvinyl alcohol.

11. A process for preparing polyvinyl acetal resins comprising reacting a polyvinyl acetate with a plurality of different aldehydes, in the presence of a deesteriflcation medium, a deesterification catalyst and 'an acetal condensation catalyst, the reaction being carried out with all of the reactants and reaction products in solution in the deesterification medium, until there is obtained a polyvinyl acetal having an acetate group content equivalent to not more than about ten percent by weight of polyvinyl acetate and a hydroxyl group content equivalent to not more than about fifteen percent by weight of polyvinyl 7 alcohol.

12. A process for preparing polyvinyl acetal resins comprising reacting a polyvinyl acetate with a plurality of different aldehydes, in the presence of a deesterification medium and an acid deesterification catalyst, the reaction being carried out with all of the reactants and reaction products in solution in the deesterification medium, until there is obtained a polyvinyl acetal having an acetate group content equivalent to not more than about ten percent by weight of polyvinyl acetate and a hydroxyl group content equivalent to not more than about fifteen percent by weight of polyvinyl alcohol.

' JAMES G. MoNALLY.

RUSSEL H. VAN DYKE. 

